Photographic silver halide color materials

Abstract

A method of forming a photographic colour image which comprises imagewise exposing a photographic silver halide colour material and processing it with an alkaline developer solution in the presence of a sulphonhydrazide developer and a heteroarylacetonitrile colour coupler thus forming a dye image by reaction of oxidised colour developing agent and the colour coupler. A colour photographic material is also provided having at least two colour-forming units sensitive to different regions of the spectrum, each having a silver halide emulsion layer, characterised in that the material contains in or adjacent said layer, a ballasted photographic colour coupler and a ballasted sulphonhydrazide colour developing agent incorporated therein in droplets of a high boiling solvent and in which the colour coupler is a heteroarylacetonitrile.

We claim: 
     
       1. A method of forming a photographic colour image which comprises imagewise exposing a photographic silver halide colour material and processing it with an alkaline developer solution in the presence of a sulphonhydrazide developer and a heteroarylacetonitrile colour coupler thus forming a dye image by reaction of oxidised sulphonhvdrazide developer and the colour coupler, the heteroarylacetonitrile colour coupler having the general formula: ##STR22## wherein R 2  is H or an alkyl or aryl group either of which may be substituted, X is --S--, --O-- or --N(R 3 )-- where R 3  is alkyl or aryl group either of which may be substituted, Y is an electron-withdrawing group having a Hammett sigma-para value greater than 0.3, and wherein the coupling position is indicated by the arrow.   
     
     
       2. A method as claimed in claim 1 in which the sulphonhydrazide developing agent has the general formula:   R--NHNH--SO.sub.2 --R.sup.1                                ( 1)     wherein R is an aryl or heterocyclic group which may be substituted, and R 1  is an alkyl or aryl group, either of which may be substituted, and   wherein R or R 1  contains a ballasting group of such size and configuration as to render the compound non-diffusible.   
     
     
       3. A method as claimed in claim 1 in which both the coupler and the developing agent are incorporated in the photogaphic material. 
     
     
       4. A method as claimed in claim 1 in which the coupler and the developing agent are incorporated in the photogaphic material in droplets of a high boiling coupler solvent. 
     
     
       5. A method as claimed in claim 4 in which both the coupler and the developing agent are co-dispersed in the same coupler solvent droplets. 
     
     
       6. A colour photographic material comprising at least two colour-forming units sensitive to different regions of the spectrum each comprising a silver halide emulsion layer characterised in that the material contains in or adjacent said layer, a ballasted photographic colour coupler and a ballasted sulphonhydrazide colour developing agent incorporated therein in droplets of a high boiling solvent and wherein the colour coupler is a heteroarylacetonitrile of the general formula (2) below, such that upon imagewise exposure of the material and processing of the element in an alkaline solution a dye image is formed by reaction of the oxidised suphonhydrazide developing agent and the colour coupler: ##STR23## wherein R 2  is H or an alkyl or aryl group either of which may be substituted, X is --S--, --O-- or --N(R 3 )-- where R 3  is alkyl or aryl group either of which may be substituted, Y is an electron-withdrawing group having Hammett sigma-para value greater than 0.3, and wherein the coupling position is indicated by the arrow.   
     
     
       7. A colour photographic material as claimed in claim 6 wherein the sulphonhydrazide developing agent has the general formula (1) below:   R--NHNH--SO.sub.2 --R.sup.1                                ( 1)     wherein R is an aryl or heterocyclic group which may be substituted, and R 1  is an alkyl or aryl group, either of which may be substituted, and   wherein R or R 1  contains a ballasting group of such size and configuration as to render the compound non-diffusible.   
     
     
       8. A colour photographic material as claimed in claim 7 in which the material is a multicolour photographic material comprising a support bearing a yellow dye image-forming unit comprised of at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, at least one magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler at least one cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler. 
     
     
       9. A colour photographic material as claimed in claim 6 in which the material is a multicolour photographic material comprising a support bearing a yellow dye image-forming unit comprised of at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, at least one magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler at least one cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler. 
     
     
       10. A colour photographic material as claimed in claim 6 in which the material is a multicolour photographic material comprising a support bearing a yellow dye image-forming unit comprised of at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, at least one magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler at least one cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler.